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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head><meta http-equiv="content-type" content="text/html; charset=UTF-8" /><title>KeepAliveFilter xref</title><link type="text/css" rel="stylesheet" href="../../../../../stylesheet.css" /></head><body><div id="overview"><a href="../../../../../../apidocs/org/apache/mina/filter/keepalive/KeepAliveFilter.html">View Javadoc</a></div><pre><a name="1" href="#1">1</a> <em class="jxr_comment">/*</em><a name="2" href="#2">2</a> <em class="jxr_comment"> * Licensed to the Apache Software Foundation (ASF) under one</em><a name="3" href="#3">3</a> <em class="jxr_comment"> * or more contributor license agreements. See the NOTICE file</em><a name="4" href="#4">4</a> <em class="jxr_comment"> * distributed with this work for additional information</em><a name="5" href="#5">5</a> <em class="jxr_comment"> * regarding copyright ownership. The ASF licenses this file</em><a name="6" href="#6">6</a> <em class="jxr_comment"> * to you under the Apache License, Version 2.0 (the</em><a name="7" href="#7">7</a> <em class="jxr_comment"> * "License"); you may not use this file except in compliance</em><a name="8" href="#8">8</a> <em class="jxr_comment"> * with the License. You may obtain a copy of the License at</em><a name="9" href="#9">9</a> <em class="jxr_comment"> *</em><a name="10" href="#10">10</a> <em class="jxr_comment"> * <a href="http://www.apache.org/licenses/LICENSE-2.0" target="alexandria_uri">http://www.apache.org/licenses/LICENSE-2.0</a></em><a name="11" href="#11">11</a> <em class="jxr_comment"> *</em><a name="12" href="#12">12</a> <em class="jxr_comment"> * Unless required by applicable law or agreed to in writing,</em><a name="13" href="#13">13</a> <em class="jxr_comment"> * software distributed under the License is distributed on an</em><a name="14" href="#14">14</a> <em class="jxr_comment"> * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY</em><a name="15" href="#15">15</a> <em class="jxr_comment"> * KIND, either express or implied. See the License for the</em><a name="16" href="#16">16</a> <em class="jxr_comment"> * specific language governing permissions and limitations</em><a name="17" href="#17">17</a> <em class="jxr_comment"> * under the License.</em><a name="18" href="#18">18</a> <em class="jxr_comment"> *</em><a name="19" href="#19">19</a> <em class="jxr_comment"> */</em><a name="20" href="#20">20</a> <strong class="jxr_keyword">package</strong> org.apache.mina.filter.keepalive;<a name="21" href="#21">21</a> <a name="22" href="#22">22</a> <strong class="jxr_keyword">import</strong> org.apache.mina.common.AttributeKey;<a name="23" href="#23">23</a> <strong class="jxr_keyword">import</strong> org.apache.mina.common.DefaultWriteRequest;<a name="24" href="#24">24</a> <strong class="jxr_keyword">import</strong> org.apache.mina.common.IdleStatus;<a name="25" href="#25">25</a> <strong class="jxr_keyword">import</strong> org.apache.mina.common.IoFilter;<a name="26" href="#26">26</a> <strong class="jxr_keyword">import</strong> org.apache.mina.common.IoFilterAdapter;<a name="27" href="#27">27</a> <strong class="jxr_keyword">import</strong> org.apache.mina.common.IoFilterChain;<a name="28" href="#28">28</a> <strong class="jxr_keyword">import</strong> org.apache.mina.common.IoSession;<a name="29" href="#29">29</a> <strong class="jxr_keyword">import</strong> org.apache.mina.common.IoSessionConfig;<a name="30" href="#30">30</a> <strong class="jxr_keyword">import</strong> org.apache.mina.common.WriteRequest;<a name="31" href="#31">31</a> <strong class="jxr_keyword">import</strong> org.slf4j.Logger;<a name="32" href="#32">32</a> <strong class="jxr_keyword">import</strong> org.slf4j.LoggerFactory;<a name="33" href="#33">33</a> <a name="34" href="#34">34</a> <em class="jxr_javadoccomment">/**</em><a name="35" href="#35">35</a> <em class="jxr_javadoccomment"> * An {@link IoFilter} that sends a keep-alive request on</em><a name="36" href="#36">36</a> <em class="jxr_javadoccomment"> * <tt>sessionIdle</tt> event with {@link IdleStatus#READER_IDLE} and sends</em><a name="37" href="#37">37</a> <em class="jxr_javadoccomment"> * back the response for the keep-alive request.</em><a name="38" href="#38">38</a> <em class="jxr_javadoccomment"> * </em><a name="39" href="#39">39</a> <em class="jxr_javadoccomment"> * <h2>Interference with {@link IoSessionConfig#setIdleTime(IdleStatus, int)}</h2></em><a name="40" href="#40">40</a> <em class="jxr_javadoccomment"> * </em><a name="41" href="#41">41</a> <em class="jxr_javadoccomment"> * This filter adjusts <tt>idleTime</tt> property for</em><a name="42" href="#42">42</a> <em class="jxr_javadoccomment"> * {@link IdleStatus#READER_IDLE} automatically. Changing the <tt>idleTime</tt></em><a name="43" href="#43">43</a> <em class="jxr_javadoccomment"> * property for {@link IdleStatus#READER_IDLE} will lead this filter to a</em><a name="44" href="#44">44</a> <em class="jxr_javadoccomment"> * unexpected behavior.</em><a name="45" href="#45">45</a> <em class="jxr_javadoccomment"> * </em><a name="46" href="#46">46</a> <em class="jxr_javadoccomment"> * <h2>Implementing {@link KeepAliveMessageFactory}</h2></em><a name="47" href="#47">47</a> <em class="jxr_javadoccomment"> * </em><a name="48" href="#48">48</a> <em class="jxr_javadoccomment"> * To use this filter, you have to provide an implementation of</em><a name="49" href="#49">49</a> <em class="jxr_javadoccomment"> * {@link KeepAliveMessageFactory}, which determines a received or sent</em><a name="50" href="#50">50</a> <em class="jxr_javadoccomment"> * message is a keep-alive message or not and creates a new keep-alive</em><a name="51" href="#51">51</a> <em class="jxr_javadoccomment"> * message:</em><a name="52" href="#52">52</a> <em class="jxr_javadoccomment"> * </em><a name="53" href="#53">53</a> <em class="jxr_javadoccomment"> * <table border="1"></em><a name="54" href="#54">54</a> <em class="jxr_javadoccomment"> * <tr></em><a name="55" href="#55">55</a> <em class="jxr_javadoccomment"> * <th>Name</th><th>Description</th><th>Implementation</th></em><a name="56" href="#56">56</a> <em class="jxr_javadoccomment"> * </tr></em><a name="57" href="#57">57</a> <em class="jxr_javadoccomment"> * <tr valign="top"></em><a name="58" href="#58">58</a> <em class="jxr_javadoccomment"> * <td>Active</td></em><a name="59" href="#59">59</a> <em class="jxr_javadoccomment"> * <td>You want a keep-alive request is sent when the reader is idle.</em><a name="60" href="#60">60</a> <em class="jxr_javadoccomment"> * Once the request is sent, the response for the request should be</em><a name="61" href="#61">61</a> <em class="jxr_javadoccomment"> * received within <tt>keepAliveRequestTimeout</tt> seconds. Otherwise,</em><a name="62" href="#62">62</a> <em class="jxr_javadoccomment"> * the specified {@link KeepAlivePolicy} will be enforced. If a keep-alive</em><a name="63" href="#63">63</a> <em class="jxr_javadoccomment"> * request is received, its response also should be sent back.</td></em><a name="64" href="#64">64</a> <em class="jxr_javadoccomment"> * <td>Both {@link KeepAliveMessageFactory#getRequest(IoSession)} and</em><a name="65" href="#65">65</a> <em class="jxr_javadoccomment"> * {@link KeepAliveMessageFactory#getResponse(IoSession, Object)} must</em><a name="66" href="#66">66</a> <em class="jxr_javadoccomment"> * return a non-<tt>null</tt>.</td></em><a name="67" href="#67">67</a> <em class="jxr_javadoccomment"> * </tr></em><a name="68" href="#68">68</a> <em class="jxr_javadoccomment"> * <tr valign="top"></em><a name="69" href="#69">69</a> <em class="jxr_javadoccomment"> * <td>Semi-active</td></em><a name="70" href="#70">70</a> <em class="jxr_javadoccomment"> * <td>You want a keep-alive request to be sent when the reader is idle.</em><a name="71" href="#71">71</a> <em class="jxr_javadoccomment"> * However, you don't really care if the response is received or not.</em><a name="72" href="#72">72</a> <em class="jxr_javadoccomment"> * If a keep-alive request is received, its response should</em><a name="73" href="#73">73</a> <em class="jxr_javadoccomment"> * also be sent back.</em><a name="74" href="#74">74</a> <em class="jxr_javadoccomment"> * </td></em><a name="75" href="#75">75</a> <em class="jxr_javadoccomment"> * <td>Both {@link KeepAliveMessageFactory#getRequest(IoSession)} and</em><a name="76" href="#76">76</a> <em class="jxr_javadoccomment"> * {@link KeepAliveMessageFactory#getResponse(IoSession, Object)} must</em><a name="77" href="#77">77</a> <em class="jxr_javadoccomment"> * return a non-<tt>null</tt>, and the <tt>policy</tt> property</em><a name="78" href="#78">78</a> <em class="jxr_javadoccomment"> * should be set to {@link KeepAlivePolicy#OFF} or {@link KeepAlivePolicy#LOG}.</em><a name="79" href="#79">79</a> <em class="jxr_javadoccomment"> * </td></em><a name="80" href="#80">80</a> <em class="jxr_javadoccomment"> * </tr></em><a name="81" href="#81">81</a> <em class="jxr_javadoccomment"> * <tr valign="top"></em><a name="82" href="#82">82</a> <em class="jxr_javadoccomment"> * <td>Passive</td></em><a name="83" href="#83">83</a> <em class="jxr_javadoccomment"> * <td>You don't want to send a keep-alive request by yourself, but the</em><a name="84" href="#84">84</a> <em class="jxr_javadoccomment"> * response should be sent back if a keep-alive request is received.</td></em><a name="85" href="#85">85</a> <em class="jxr_javadoccomment"> * <td>{@link KeepAliveMessageFactory#getRequest(IoSession)} must return</em><a name="86" href="#86">86</a> <em class="jxr_javadoccomment"> * <tt>null</tt> and {@link KeepAliveMessageFactory#getResponse(IoSession, Object)}</em><a name="87" href="#87">87</a> <em class="jxr_javadoccomment"> * must return a non-<tt>null</tt>.</td></em><a name="88" href="#88">88</a> <em class="jxr_javadoccomment"> * </tr></em><a name="89" href="#89">89</a> <em class="jxr_javadoccomment"> * <tr valign="top"></em><a name="90" href="#90">90</a> <em class="jxr_javadoccomment"> * <td>Deaf Speaker</td></em><a name="91" href="#91">91</a> <em class="jxr_javadoccomment"> * <td>You want a keep-alive request to be sent when the reader is idle, but</em><a name="92" href="#92">92</a> <em class="jxr_javadoccomment"> * you don't want to send any response back.</td> </em><a name="93" href="#93">93</a> <em class="jxr_javadoccomment"> * <td>{@link KeepAliveMessageFactory#getRequest(IoSession)} must return</em><a name="94" href="#94">94</a> <em class="jxr_javadoccomment"> * a non-<tt>null</tt> and</em><a name="95" href="#95">95</a> <em class="jxr_javadoccomment"> * {@link KeepAliveMessageFactory#getResponse(IoSession, Object)} must</em><a name="96" href="#96">96</a> <em class="jxr_javadoccomment"> * return <tt>null</tt>.</td></em><a name="97" href="#97">97</a> <em class="jxr_javadoccomment"> * </tr></em><a name="98" href="#98">98</a> <em class="jxr_javadoccomment"> * <tr valign="top"></em><a name="99" href="#99">99</a> <em class="jxr_javadoccomment"> * <td>Silent Listener</td></em><a name="100" href="#100">100</a> <em class="jxr_javadoccomment"> * <td>You don't want to send a keep-alive request by yourself nor send any</em><a name="101" href="#101">101</a> <em class="jxr_javadoccomment"> * response back.</td> </em><a name="102" href="#102">102</a> <em class="jxr_javadoccomment"> * <td>Both {@link KeepAliveMessageFactory#getRequest(IoSession)} and</em><a name="103" href="#103">103</a> <em class="jxr_javadoccomment"> * {@link KeepAliveMessageFactory#getResponse(IoSession, Object)} must</em><a name="104" href="#104">104</a> <em class="jxr_javadoccomment"> * return <tt>null</tt>.</td></em><a name="105" href="#105">105</a> <em class="jxr_javadoccomment"> * </tr></em><a name="106" href="#106">106</a> <em class="jxr_javadoccomment"> * </table></em><a name="107" href="#107">107</a> <em class="jxr_javadoccomment"> * Please note that you must implement</em><a name="108" href="#108">108</a> <em class="jxr_javadoccomment"> * {@link KeepAliveMessageFactory#isRequest(IoSession, Object)} and</em><a name="109" href="#109">109</a> <em class="jxr_javadoccomment"> * {@link KeepAliveMessageFactory#isResponse(IoSession, Object)} properly</em>⌨️ 快捷键说明
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